Sound amplifier



Feb. 7, 1939. w. R. ALLISON 2,146,325

SOUND AMPLIFIER Filed Feb. 9, 1937 at... Feb. 1, 1939 a a 2,146,325

UNITED STATES PATENT OFFICE SOUND AMPLIFIER.

William 1L Allison, Cnliman, Ala.

Application February 9, 1937, Serial No. 124,945

1 Claim. (Cl. 181-27) This invention relates to sound amplifiers and reversed upon themselves, to economize in length, has for an object to provide an amplifier for radio these horns being shown as substantially irustoreceiving sets or other apparatus, adapted to propyramidal in cross section, although they may be duce clearer and more natural reproduction than circular, oval, or of other desired cross sectional 5 hitherto possible. area. 5

A further object of the invention is to provide The horns are arranged concentrically in juxtaa second amplifier having tubular horn-like posed position about a common axis of sound members of respectively difi'erent lengths providprojection indicated by the line C--D in Figure 3, ing air columns tuned respectively to one-hall and each horn is of a respectively difi'erent length 0 the wave length of notes of the scale so as to than the next succeeding horn, for example, the 1 reproduce accurately notes of one-half the wave longest horn I, being 01' a predetermined length length, or the harmonics of one, two, four, eight to correspond to one-half the wave length of the or more within any predetermined column. low G note, on the diatonic scale, or do, the next A further object is to provide an amplifier of horn in advance being of a length corresponding this type in which the emergent wave is substanto one-half the wave length of the next higher tially in the same plane as the beginning of the note A, or re on the scale, and so forth, eight wave, the different respective lengths of the horns of the horns being shown, of respectively debeing accomplished by arranging the rear ends creasing length from the low G to the G an of the horns in stepped relationship. octave above.

A further object is to provide a sound amplifier The horns are supported upon a spider 8 iorm- 20 of this type adapted to amplify all notes on the ing separators between the horns, the spider being diatonic scale regardless of pitch, adiatonic scale mounted at the entrance of the horns, as best being the only scale of true notes or tones, all shown in Figure 3. The horns are all spaced other notes being hall. tones and not pleasing to slightly apart at their intake ends in the spider to the human ear. provide an air vent 20.

A further object is to provide a sound amplifier A panel 2i of sound insulating material is disor loud speaker having columns of air set in posed between the horns at the rear ends thereof motion at a common source, the air columns and between the panel and the spider there exists being of respectively different lengths, the length an air chamber 24 adapted to receive a convenof the air column corresponding to the lowest tional reproducer 22 of the magnetic or dynamic 30 note G being of predetermined length and all type, the input wires 22 of which may be conof the columns being respectively 0! predeternected to the audio-frequency posts of any conmined shorter length to correspond to the wave ventional radio receiving set or other sound relengths of progressively higher notes in the scale. producing apparatus.

With the above and other objects in view the Vibrations set up in the air chamber 2! between 35 invention consists of certain novel details of conthe reproducer 22 and the intake ends of the struction and combinations of parts hereinafter horns will be amplified by the air columns in the fully described and claimed, it being understood horns. The small vent opening 20 permits freethat various modifications may be resorted to dom of fluctuations in the air space in front of 40 within the scope of the appended claim withthe reproducer 22 without back pressure. It will 40 out departing from the spirit or sacrificing any be further pointed out that the air columns 01' 0f the a van es o e nt the various horns, set in motion by a common In the accompanying drawing forming part of source (the reproducer 22) have a common point this specification, of entry in the horns and although the columns 4 5 Figure 1 is a side elevation of a sound amplifier are of respectively difierent lengths all are united constructed in accordance with the invention. in the same wave plane, designated by the nu- Figure 2 is a cross sectional view taken on the meral 25 at the front of the horns, so that the line 2-2 of Figure 1. emergent wave is substantially in the same wave Figure 3 is a longitudinal sectional view taken plane as the beginning of the wave in the sepaon the line 3-3 of Figure 2. rator or spider 9. The variations in length of the 50 Referring now to the drawing in which like horns respectively are accomplished by arrang characters of reference designate similar parts ing the rear ends of the horns in stepped relationin the various views, the reference numerals l ship. v to I inclusive designate respectively tubular horns More specifically the central chamber tapers ti or substantially U-shape longitudinal section, or from a large end to a small end shown in Figure 3 u and is formed or side walls 8| forming an octagon I s as shown in Figure 2, there being radially disposed division walls 3| extending outwardly from the meeting longitudinal edges oi. the side walls 01' 5 the chamber. Serpentine walls 32 are disposed between the radial walls, each having a reverse bend 33 intermediate the ends thereof to economize in length, the inner ends of the serpentine walls having reverse bends 34 spaced apart to 10 provide the before mentioned vent opening 20.

The serpentine walls coact with the radial walls 3| and side walls 30 of the chamber to form horns of respectively diflerent lengths arranged in the form of an annulus around an axis CD and hav- 5 ing the intermediate reverse bends stepped to provide a loud speaker of compact box-like structure in which the outlet ends of the horns lie in the same plane.

The amplifier may be formed of any suitable 2o non-resonant material and the panel 2| may be formed of a-suitable pad of soft sound absorbing material which will completely fill the opening at the rear of the air chamber 24 in the device and absorb all tones from the rear of the reproducer,

25 which tones in practice are found to be not true tones.

From the above description it is thought that the construction and operation of the invention will be fully understood without further explanation.

What is claimed is:

A sound amplifier comprising a central chamber tapering from a large end atthe rear to a small end at the front and having side walls tormamasae p i ing substantially an Octagon. radially vision walls extending outwardly from the meeting longitudinal edges of the side walls of the chamber, serpentine walls between the radial walls, each serpentine wall having a reverse bend intermediate its ends to economize in length and form a loud speaker horn oi box-like structure, the inner end of each serpentine wall having a reverse bend disposed at the smaller end of the chamber coacting with the walls of the chamber.

in forming a sound intake end for the horn. all of the horns being arranged in an annularseries around the longitudinal axisof the chamber, a spider forming division walls between the serpentine walls and walls of the chamber at the sound entrance ends of the horns. a sound abdisposeddh sorbing panel in the chamber in said intermediate reversed bends of the serpentine walls, a sound producer in the chamber between the sound absorbent panel andthe spider, there being an opening between the reversely bent sound entrance ends of the horns venting the chamber to the atmosphere, the horns-being of such respective lengths as to provide air columns tuned respectively to one-half the wave length or an octave of notes of a diatonic scale to produce accurately notes of one-half the wave length or the harmonics of l, 2, 4, 8 or more harmonics of a note in any predetermined column, the outlet ends of the horns all terminating in a single plane-the reverse bends ot the horns being disposed in stepped relation to permit the outlet ends-lying in the same plane.

WILLIAM R. ALLISON.- 

